An Australian-led peacekeeping force began hunting Thursday for rebel soldiers suspected in assassination attempts on East Timor's president and prime minister, both of whom were attacked Monday. The attempts on the lives of President Jose Ramos-Horta and Prime Minister Xanana Gusmao highlight the nation-building challenges faced by East Timor, Asia's newest country.

Soldiers, helicopters, and armored vehicles have been searching the scrub outside the capital, Dili, for the suspects, the BBC reported. Australian doctors said Mr. Ramos-Horta, who won a Nobel Peace Prize for campaigning against Indonesia's occupation, was stable, recovering from gunshot wounds. But he remains in serious condition. Ramos-Horta was attacked by about 10 men near his home as he returned from a morning walk, officials said. His guards fired back, killing rebel leader Alfredo Reinado and one of his followers. Mr. Gusmao was unhurt in a separate attack Monday.

The Associated Press reports that East Timor has extended a state of emergency imposed after the shooting. Gusmao asked parliament for the 10-day extension, saying it was "in the interests of the people," so they could, "live in peace and normalcy." Lawmakers agreed to the emergency order, which bans demonstrations, gives police extended powers, and imposes a nighttime curfew. A United Nations force has been in East Timor since a wave of street violence in mid-2006.

East Timor's neighbors, Australia, Japan, and Indonesia, have been increasingly concerned about the stability of the six-year-old nation. Civil war followed Portugal's abrupt decolonization in 1975 and caused a flood of refugees to cross the border into Indonesia, giving it the pretext to begin an invasion and a 24-year occupation. In 1999, East Timor voted to break from Indonesia in a UN-sponsored plebiscite, and the country has been under UN tutelage ever since.

Mr. Reinado's supporters, involved in the 2006 unrest, are thought to have carried out Monday's attacks. Reinado, a former military officer, had been on the run with a group of followers for almost two years. In 2006, foreign media blamed Reinado for sparking the wave of violence two years ago after he and his supporters deserted the Army, triggering clashes that killed 37 people and led to the collapse of East Timor's postindependence government. Reinado was charged with murder over the events, but he retained his folk-hero status among some of East Timor's unemployed and disenchanted youth.

Observers in East Timor are also questioning the lapse in security that led to the attack. The Australian said it had received a latter from the Australian Commander of the International Stabilization Force (ISF) Brigadier John Hutcheson to Reinado's lawyer, Benny Benevides, assuring him of the rebel leader's safety. "Your client is hereby assured that, subject to his complying with any preagreed arrangements during the dialogue period, your client's movements will not be interfered with," the letter said.

Brigadier Hutcheson wrote that the stabilization force was obliged to detain anyone seen carrying an unauthorized weapon, but it seemed Reinado had been granted an exception, "despite the fact he was a prison escapee facing murder charges."

Some analysts expect Reinado's supporters to stage violent demonstrations. So far, however, the country has been mostly calm since the attacks. Australian soldiers on Wednesday searched cars for weapons at checkpoints and armored UN vehicles guarded top politicians.

Rudd said the Australian Defence Forces (ADF) have secured key buildings and deployed more broadly throughout Dili and increased their presence in East Timor's districts. UN forces, including Australian troops, which have been in East Timor since 2006, following the violence between rebel forces and East Timorese police.

Ramos-Horta has waived an arrest warrant for Reinado, deciding instead to seek peaceful negotiations with him.

The UN and East Timorese police have begun a joint investigation and the commander of East Timor's defense force has called for the appointment of a panel of inquiry.

The deployment of more Australian troops poses a danger to the standing of East Timorese politicians in general and the Ramos-Horta government. Such a deployment would mean East Timor would have to rely on foreign forces to protect itself.